This invention relates to continuously operating presses for the manufacture of panels, such as chipboards, fiberboards, or the like, which presses have two superimposed endless belts consisting of mutually linked plates and rotating about axes arranged horizontally and in parallel to each other. The mutually facing runs of these belts are movable preferably by means of drivable pressure rolls in the same direction, and each endless platen belt is encompassed by a further endless belt. Such presses further may include means for adjusting at least one of the ends of several superimposed pressure roll pairs transversely to their axial extension in the horizontal plane, these means being effective on the bearings of the upper and lower pressure rolls. Such a press is conventional (DAS [German Published Application] No. 2,220,553). The adjustment of the bearings of the pressure rolls, however, can only be accomplished if the press is deactivated for a short period of time.
Therefore, the invention is primarily concerned with the problem of making the adjustment possible without having to deactivate the press. This problem is solved, in accordance with this invention, by providing that at least the superimposed bearings of the pressure rolls which are first -- as seen in the feeding direction of the press -- are supported by needle bearings or the like guided in tracks. If the needle bearings are provided directly above and/or below the bearings of the pressure rolls in accordance with a first preferred arrangement of the invention, this is sufficient in case the pressure forces exerted on the pressure rolls are relatively minor, as is the case in continuously operating rough presses.
However, this just-mentioned construction includes the disadvantage that the upper bearings of the pressure rolls are shifted with respect to the pistons of the hydraulic cylinders controlling the rolls. These cylinders (pistons) tend to urge the pressure rolls against the endless platen belts. Consequently, the pressure forces exerted by the hydraulic cylinders are no longer effective centrally on the bearings and thus no longer centrally on the pressure rolls, which latter feature is important if the pressure forces are relatively high, as is the case, for example, in continuously operating finishing presses.
Therefore, this invention also contemplates arrangements solving the further problem of assuring that the bearings and thus also the pressure rolls, in spite of their movability, are always under a centrally effective force, so that such needle bearings can also be installed in continuously operating finishing presses wherein the required contact pressures are substantially higher than in rough presses of the same type of construction. This further problem has been solved, in accordance with the invention, by disposing the needle bearings or the like, guided in tracks, at least between the first supports of the pressure cylinders arranged in the inlet zone of the press and pertaining to the upper pressure rolls and/or between the first supports of the bearings of the lower pressure rolls. It is especially suitable to combine the needle bearings associated with several pressure rolls into respectively one group, because in such a case the number of needles (pins) or the like can be increased. Thereby, the frictional forces occurring during the shifting of the bearings are reduced to a greater extent, and this has a favorable effect especially in case of relatively long presses of this type, as was demonstrated by experiments. It is, of course, also contemplated to support further pressure rolls, i.e. for example pressure rolls of other groups, in accordance with the invention.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing, which shows, for purposes of illustration only, a single embodiment in accordance with the present invention.